Patent GB-495924-A (GB)
Title: Improvements in the recovery of aromatic hydrocarbons and phenols
IPC: C07C7/10
Filed: 1938-01-18
Abstract: Hydrocarbon mixtures boiling within the benzine range are treated to remove aromatic hydrocarbons by extracting with a selective solvent for aromatic hydrocarbons, separating the undissolved portion, washing the extract with liquefied normally gaseous hydrocarbons at -40 DEG  C. or lower, and freeing the washed product from selective solvent.  Phenols, if initially present, are removed with the aromatic hydrocarbons.  Selective solvents specified are liquid sulphur dioxide, aniline, methylaniline, toluidine, furfurol, acetonitrile, dichlorethyl ether, and triethylene glycol.  Extraction may be effected at low temperature, e.g. -20 to -40 DEG  C. with liquid SO2.  For washing the extract, liquefied paraffins, e.g. methane, ethane or propane, are particularly suitable.  1 or 2 volumes of selective solvent or washing agent for each volume of initial mixture may, for example, be used.  Increased pressures may be used in either or both stages.  The initial mixture may be passed into the bottom of a packed vessel, liquid SO2 being led into the upper part, or a number of vessels in series may be employed. Further liquid SO2 may be added before or during the subsequent washing.  In an example, a benzine fraction containing 45 per cent of toluene is extracted at -45 DEG  C. with liquid SO2, and the separated extract washed at -45 DEG  C. with propane.  Toluene is recovered from the SO2 layer.  A better separation is effected by working at -80 DEG  C.  Specifications 452,537, 466,730, and 477,050 are referred to.  The Specification as open to inspection under Sect. 91 comprises the treatment of any initial material containing aromatic hydrocarbons or their oxygen derivatives such as phenols and cresols, in particular benzines obtained by pressure hydrogenation of coals.  It is not limited to the use of temperatures of -40 DEG  C. or lower in the washing stage, -10 DEG  C. or lower being mentioned. This subject-matter does not appear in the Specification as accepted.ALSO:Aromatic hydrocarbons, e.g. benzene, toluene, and xylene are recovered from hydrocarbon mixtures boiling within the benzine range by extracting with a selective solvent for aromatic hydrocarbons, separating the undissolved portion, washing the extract with liquefied normally gaseous hydrocarbons at -40 DEG  C. or lower, and freeing the washed product from selective solvent. Phenols, if initially present, are recovered with the aromatic hydrocarbons. Selective solvents specified are liquid sulphur dioxide, aniline, methylaniline, toluidine, furfurol, acetonitrile, dichlorethyl ether, and triethylene glycol. Extraction may be effected at low temperature, e.g. - 20 to - 40 DEG  C. with liquid SO2.  For washing the extract, liquefied paraffins, e.g. methane, ethane or propane, are particularly suitable.  1 or 2 volumes of selective solvent or washing agent for each volume of initial mixture may, for example, be used. Increased pressures may be used in either or both stages.  The initial mixture may be passed into the bottom of a packed vessel, liquid SO2 being led into the upper part, or a number of vessels in series may be employed.  Further liquid SO2 may be added before or during the subsequent washing.  The small amount of aromatic hydrocarbons removed in the washing agent may be recovered by a further extraction and washing.  In an example, a benzine fraction containing 45 per cent of toluene is extracted at - 45 DEG  C. with liquid SO2, and the separated extract washed at - 45 DEG  C. with propane.  Toluene is recovered from the SO2 layer.  A better separation is effected by working at - 80 DEG  C.  Specifications 452,537, 466,730, and 477,050, [all in Group III], are referred to. The Specification as open to inspection under Sect. 91 comprises the treatment of any initial material containing aromatic hydrocarbons or their oxygen derivatives such as phenols and cresols, in particular benzines obtained by pressure hydrogenation of coals.  It is not limited to the use of temperatures of - 40 DEG  C. or lower in the washing stage, - 10 DEG  C. or lower being mentioned.  This subject-matter does not appear in the Specification as accepted.